Helical states of nonlocally interacting molecules and their linear stability: geometric approach

The equations for strands of rigid charge configurations interacting nonlocally are formulated on the special Euclidean group, SE(3), which naturally generates helical conformations. Helical stationary shapes are found by minimizing the energy for rigid charge configurations positioned along an infinitely long molecule with charges that are off-axis. The classical energy landscape for such a molecule is complex with a large number of energy minima, even when limited to helical shapes. The question of linear stability and selection of stationary shapes is studied using an SE(3) method that naturally accounts for the helical geometry. We investigate the linear stability of a general helical polymer that possesses torque-inducing non-local self-interactions and find the exact dispersion relation for the stability of the helical shapes with an arbitrary interaction potential. We explicitly determine the linearization operators and compute the numerical stability for the particular example of a linear polymer comprising a flexible rod with a repeated configuration of two equal and opposite off-axis charges, thereby showing that even in this simple case the non-local terms can induce instability that leads to the rod assuming helical shapes.Comment: 34 pages, 9 figure

Cities in fiction: Perambulations with John Berger

This paper explores selected novels by John Berger in which cities play a central role. These cities are places, partially real and partially imagined, where memory, hope, and despair intersect. My reading of the novels enables me to trace important themes in recent discourses on the nature of contemporary capitalism, including notions of resistance and universality. I also show how Berger?s work points to a writing that can break free from the curious capacity of capitalism to absorb and feed of its critique

“A special kind of city knowledge”: innovative clusters, tacit knowledge and the ‘Creative City’

That the cultural industries are highly networked and operate in clusters is now well established. The notion of cluster is linked to the idea of place-based advantage with cultural industries gaining competitive advantage from mobilising the resources of places to compete in global markets. ‘Place’ in the cultural industries is frequently taken to be the city where city is seen as the key resource for cultural industry clusters and a primary point of intervention for cultural industry policy in creative city policy making. In this article I want to look at some of the implications of these moves for both academic research and policy discussion. The reasons for this emphasis on policy relates to some large questions of urban governance and cultural politics surrounding the proactive government of clusters which are raised by recent work on the cultural industries, notably by Alan Scott

Optimization and Validation of the Bode TM Buccal DNA CollectorTM in Conjunction with the AmpFLSTR® Identifiler® Direct PCR Amplification Kit for Single Source Reference Samples.

DNA analysis for human identification is a multi-step process culminating in the generation of a DNA profile unique to the contributor of the biological sample. In order for human identification by way of DNA analysis to be successful, comparisons of a known sample to an unknown sample must be made. Processing of the known or reference samples should be efficient, reliable and reproducible. The Buccal DNA Collector™ (Bode Technology Group, Lorton, VA) used in conjunction with the AmpFLSTR® Identifiler® Direct PCR Amplification Kit (Applied Biosystems, Foster City, CA) has been shown to be an effective method for processing single source reference samples. This technique can be reliably applied to the processing of samples for DNA databasing, paternity or reference samples for forensic casework

Efficient Calculation of Schwarz–Christoffel Transformations for Multiply Connected Domains Using Laurent Series

Click on the DOI link to access the article (may not be free).We discuss recently developed numerics for the Schwarz–Christoffel transformation for unbounded multiply connected domains. The original infinite product representation for the derivative of the mapping function is replaced by a finite factorization where the inner factors satisfy certain boundary conditions derived here. Least squares approximations based on Laurent series are used to satisfy the boundary conditions. This results in a much more efficient method than the original method based on reflections making the accurate mapping of domains of higher connectivity feasible.Peer reviewe